Fluorides in nanoporous, electrically-conductive scaffolding matrix for metal and metal-ion batteries

Abstract

A battery electrode composition is provided that comprises composite particles. Each composite particle may comprise, for example, active fluoride material and a nanoporous, electrically-conductive scaffolding matrix within which the active fluoride material is disposed. The active fluoride material is provided to store and release ions during battery operation. The storing and releasing of the ions may cause a substantial change in volume of the active material. The scaffolding matrix structurally supports the active material, electrically interconnects the active material, and accommodates the changes in volume of the active material.

The invention claimed is: 
     
       1. A battery electrode composition comprising composite particles, each composite particle comprising:
 active fluoride material provided to store and release ions during battery operation, whereby the storing and releasing of the ions causes a change in volume of the active material; 
 a nanoporous, electrically-conductive scaffolding matrix within which the active fluoride material is disposed, wherein the scaffolding matrix structurally supports the active material, electrically interconnects the active material, and accommodates the changes in volume of the active material; and 
 a shell at least partially encasing the active fluoride material and the scaffolding matrix, the shell being substantially impermeable to electrolyte solvent molecules and configured to block contact between the active fluoride material arranged inside of the shell and the electrolyte solvent molecules arranged outside of the shell. 
 
     
     
       2. The battery electrode composition of  claim 1 , wherein the scaffolding matrix comprises pores having an average characteristic pore width in the range of about 1 nanometer to about 10 nanometers. 
     
     
       3. The battery electrode composition of  claim 1 , wherein the active fluoride material comprises a first metal fluoride and a second metal fluoride. 
     
     
       4. The battery electrode composition of  claim 1 , wherein the shell of each composite particle is substantially permeable to the ions stored and released by the active fluoride material. 
     
     
       5. The battery electrode composition of  claim 1 , wherein the shell comprises an active material layer, and wherein the active material layer is formed from a different active material than the active fluoride material disposed within the scaffolding matrix. 
     
     
       6. The battery electrode composition of  claim 5 , wherein the active material of the active material layer has a lower capacity relative to the active fluoride material. 
     
     
       7. The battery electrode composition of  claim 1 , wherein the shell comprises a porous layer having a smaller average pore size than the scaffolding matrix. 
     
     
       8. The battery electrode composition of  claim 7 , wherein pores in the porous layer of the shell are infiltrated with the same active fluoride material as the active fluoride material disposed within the scaffolding matrix. 
     
     
       9. The battery electrode composition of  claim 1 , wherein the shell is a composite material comprising an inner layer and an outer layer. 
     
     
       10. The battery electrode composition of  claim 9 , wherein the inner layer is a porous layer having a smaller average pore size than the scaffolding matrix, and wherein the outer layer is (i) a protective layer formed from a material that is substantially impermeable to electrolyte solvent molecules or (ii) an active material layer formed from an active material that is different from the active material confined within the scaffolding matrix. 
     
     
       11. The battery electrode composition of  claim 1 , wherein the shell is a composite material comprising two or more materials arranged in an interpenetrating configuration such that each of the materials of the composite material contacts the scaffolding matrix. 
     
     
       12. The battery electrode composition of  claim 1 , each composite particle further comprising external channel pores extending from an outer surface of the scaffolding matrix towards the center of the scaffolding matrix, providing channels for diffusion of the ions into the active material disposed within the scaffolding matrix, wherein at least some of the external channel pores are filled with (i) a porous material having a different microstructure than the scaffolding matrix, (ii) an active material that is different from the active fluoride material disposed within the scaffolding matrix, and/or (iii) a solid electrolyte material. 
     
     
       13. The battery electrode composition of  claim 1 , each composite particle further comprising a protective material at least partially penetrating the scaffolding matrix with a radial-varying composition along a radius of the particle, the protective material being substantially permeable to the ions stored and released by the active fluoride material. 
     
     
       14. The battery electrode composition of  claim 1 , wherein the active fluoride material is confined to the scaffolding matrix throughout the changes in volume of the active material. 
     
     
       15. The battery electrode composition of  claim 1 , wherein the active fluoride material and the scaffolding matrix are part of an electrolyte-free core that is at least partially encased by the shell. 
     
     
       16. A method of fabricating a battery electrode composition comprising composite particles, the method comprising:
 providing an active fluoride material to store and release ions during battery operation, whereby the storing and releasing of the ions causes a change in volume of the active material; 
 forming a nanoporous, electrically-conductive scaffolding matrix within which the active fluoride material is disposed, wherein the scaffolding matrix structurally supports the active material, electrically interconnects the active material, and accommodates the changes in volume of the active material; and 
 forming a shell at least partially encasing the active fluoride material and the scaffolding matrix, the shell being substantially impermeable to electrolyte solvent molecules and configured to block contact between the active fluoride material arranged inside of the shell and the electrolyte solvent molecules arranged outside of the shell. 
 
     
     
       17. The method of  claim 16 , wherein forming the scaffolding matrix comprises:
 forming a carbon-containing precursor; 
 oxidizing and carbonizing the carbon-containing precursor to form a carbonized particle; and 
 activating the carbonized particle at elevated temperature to form the scaffolding matrix with a pore volume of greater than 50 vol. %. 
 
     
     
       18. The method of  claim 16 , where the active fluoride material-infused scaffolding matrix is formed as a powder comprising particles, the method further comprising:
 mixing the active fluoride material-infused scaffolding matrix particles with a binder; 
 casting the binder-bonded particles onto a metal foil current collector. 
 
     
     
       19. The method of  claim 16 , wherein at least a portion of the shell material is deposited by chemical vapor deposition. 
     
     
       20. The method of  claim 16 , wherein at least an outer portion of the shell is deposited electrochemically during one or more initial battery cycles, during which electrochemical decomposition of at least some electrolyte components occurs.